In the event of a claim, am I only liable up to the amount of my security deposit?

In the event of an accident, you are liable only up to the amount of the security deposit you have provided, unless you have failed to comply with your contractual obligations or the law, or simply have not exercised due care while sailing. For example, if an accident occurs while you are sailing at night (without the rental company’s permission), if you set sail in dangerous weather conditions, if you caused damage to the boat while intoxicated, or if you handled fireworks or explosives on board the boat, the rental company’s insurance will not cover the incident, and the rental company will pursue legal action against you. Simply put, in these cases, the incident is not covered by the boat’s insurer, so the costs will be borne entirely by the rental company (not just up to a deductible), so it makes sense for the rental company to ask you to cover them.

Similarly, even without an accident, if you are fined or if you have not paid port fees, for example, you will be responsible for paying them, even if the total exceeds the amount of your security deposit (because, again, the rental company’s insurance will not cover these expenses).